A natural human optic typically has a thickness of about 5.0 mm. Light rays entering the cornea and passing to the optic typically travel about 7.0 to 8.0 mm. Light rays pass from the optic in a cone of light with its apex at the retina. The natural lens provides only a limited degree of depth of focus with clear vision over a limited range of distances.
The present invention provides an optic which is only a fraction the thickness of the natural lens. Whereas the natural lens is about 5.0 mm thick, the lens of the invention may typically be 1.0 mm and may range from about 0.6 mm to 1.5 mm. The distance from the cornea to the optic of the invention is about 7.0-8.0 mm, whereas with a natural lens, the light rays travel only about 3.5 mm from cornea to optic. Light rays refracted by and exiting the optic define a cone of light much smaller in cross-sectional area than the natural lens, and therefore impinge on the retina in a smaller area. The much smaller cone provides greatly increased depth of focus in comparison with a natural lens, and thus enables clear vision over a long range of distances. In effect, the invention provides effective accommodation as between near and far vision, and a person is enabled to view accurately over a wide range of distances. The optic is positioned much farther from the cornea than a natural lens, and this increase of distance minimizes the distance optical power change. The further posterior the optic, the higher the power of the optic and the less movement required for a given power change. The lens according to the invention is rigid, the haptics being rigidly connected to the optic, and the lens is vaulted posteriorly. Thus, the distance between the cornea and the optic is maximized and the distance of travel of light rays between cornea and optic is increased.
The rigid lens causes the optic to move with the periphery of the capsular bag in response to ciliary muscle changes, particularly for near vision.